The present invention relates to a clamp band for vehicle brakes and more particularly pertains to a clamp band for spring brakes which prevents the disengagement of the two chambers.
A conventional spring brake generally comprises a first chamber, a second chamber, a diaphragm, a spring and a pushrod connecting to a braking device such as a brake shoe or brake pad. The diaphragm is placed between the two chambers. The spring is heavily coiled between the diaphragm and the bottom of the first chamber. By controlling the amount of air pressure applied to the diaphragm and thereby controlling the compression of the spring, the driver can apply or release the brake. As a significant amount of energy is stored in the coiled spring, it is vital to hold the two chambers and the diaphragm in place to prevent the spring from bursting out of the first chamber.
Double diaphragm spring brakes are also available in the marketplace. A conventional double diaphragm spring brake generally comprises a service chamber and a parking chamber in tandem. The parking chamber comprises a first chamber, a second chamber, a diaphragm, a power spring and a pushrod similar to those as mentioned above. The service chamber also comprises a first chamber, a second chamber, a diaphragm, a return spring and a pushrod similar to those as mentioned above. The second chamber of the parking chamber and the first chamber of the service chamber shares a double cup shaped flange case which has a divider wall separating the second chamber of the parking chamber from the first chamber of the service chamber. The pushrod of the parking chamber connects to the diaphragm of the service chamber, and the pushrod of the service chamber connects from the diaphragm of the service chamber to a braking device such as a brake shoe or brake pad. The service brake system in the service chamber applies and releases the brakes when a driver uses the brake pedal during normal driving. The parking brake system in the parking chamber applies and releases the parking brakes when a driver uses the parking brake control. The emergency brake system uses parts of the service and parking brake systems to stop the vehicle in the event of a brake system failure. As a significant amount of energy is stored in the power spring, it is vital to hold the two chambers of the parking chamber and the diaphragm in place to prevent the power spring from bursting out of the parking chamber.
To this end, a conventional spring brake is typically equipped with a clamp band to engage the two chambers together with the diaphragm in between. However, if a user inadvertently loosens or disassembles the clamp band by loosening a screw thereon, or if the clamp band is loosened accidentally owing to, for example, a bump to the vehicle, or if the clamp band becomes out of order and fails to engage the chambers properly, the diaphragm is no longer securely fastened and thus can no longer keep the spring in place. As a result, the spring together with the diaphragm and the second chamber may burst away from the first chamber. In such a case, anybody in the surrounding area may be injured or even killed by the parts bursting away from the first chamber, let alone damage is likely to be caused to properties in the neighborhood.
With a view to preventing such incidents, some spring brakes have the housing of the first chamber and the clamp band being cast as one integral body. The second chamber is fastened to the first chamber by the method of spinning. The two chambers are then permanently joined together. Although such arrangement can prevent any accidental disengagement of the two chambers, it is susceptible of higher production costs and lower manufacturing efficiency. Moreover, if any component has any defect or if there is any error or abnormality during the assembling procedures, the air brake may fail to function properly and may not be repaired and will have to be disposed of, which results in a waste of resources.